FeS2 Crystal Lattice Promotes Nanostructure and Enhances Electrocatalytic Performance of WS2 Nanosheet for Oxygen Evolution Reaction
The control of surface elements and nanostructures is one of the effective ways to design and synthesize high performance catalysts. Herein, we, for the first time, prepare FeS2 crystal lattice on WS2 nanosheet (FeS2 CL@WS2 NS) by solvothermal methods for oxygen evolution reaction (OER). FeS2 CL effectively prevents the oxidation and aggregation of WS2 nanosheets and increases electrochemical active surface area. The abundant surface defect in FeS2 CL@WS2 NS electrocatalyst reduces the stress between crystal lattices of FeS2 and that of WS2. The overpotential (260 mV) of FeS2 CL@WS2 NS electrocatalyst for OER at a current density of 10 mA cm−2 is superior to that of WS2 NS/Ni foam (310 mV) and IrO2/Ni foam (300 mV) in 1.0 M KOH solution. Electrochemical-kinetic study shows that the tafel slope of 54 mV/decade for FeS2 CL@WS2 NS electrocatalyst is lower than those of WS2 NS (102 mV/decade) and IrO2/Ni foam (77 mV/decade). In addition, the charge transport resister (2.3 Ω) of FeS2 CL@WS2 NS electrocatalyst for OER is smaller than that of WS2 NS. These faster kinetics properties, in turn, explain the high catalytic activity of FeS2 CL@WS2 NS electrocatalyst for OER. The XPS and HRTEM results of post stability sample confirm that Fe2+, W4+ are oxidized after durability measurement. Thus, we think that FeS2 CL@WS2 NS electrocatalyst is a promising candidate for efficient, low-cost, and stable non-noble-metal-based OER electrocatalysts.